Surface Enhanced Raman Scattering (SERS) is a technique using Raman scattering for enhancing the detection of molecular species through the excitation of Plasmon modes and their coupling to molecular vibrational modes. In other words, Raman scattering is the inelastic scattering of photons that can provide vibrational fingerprints of molecules. The substrate surface on which the detection of molecular species is taking place, as well as the material of the substrate surface affects the strength and intensity of the Raman scattering.
Currently available substrates for use in SERS suffer from various deficiencies in the enhancement and detection of Raman scattering. Raman scattering signals are generally very weak, especially on flat substrates. The weak Raman signal can make it difficult to detect and measure the Raman scattering signal and consequently make it difficult to detect and identify the molecular species. Furthermore, even if the available substrate enhances the Raman scattering signal, the enhanced Raman scattering signal is usually in a localized area(s) on the substrate and not uniform across the substrate surface. The area of the localized enhanced Raman scattering signal is exponentially small compared to the entire area of the substrate surface. The large disparity between the area of the Raman scattering signal and the area of the substrate surface make it burdensome to search and locate the signal and consequently burdensome to detect and identify the molecular species.
Moreover, current substrates are expensive and difficult to manufacture. The manufacturing of the substrates can require burdensome and expensive lithographically patterned masking and etch-stopping layers. The lithography process also limits the density of the features on the substrate surface that enhances Raman scattering and thus the intensity of the observed Raman signal.
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